J35A4 vs. J35A6?

What's the physical difference between a Honda J35A4 and a J35A6? I have an A6 i'm wanting to drop into my E30, but I'm having some serious issues finding parts for it. I am, however, finding more parts for the A4. Seeing as the A4 was used in the 2004 Pilot and the A6 was used in the 2005 Pilot, there can't be much of a difference, right? I'm not worried about electrical differences as i'm planning on running a standalone ECU anyways.

I remember being told by Marked Motorsports that Honda has upwards of 10+ (or some number equally ridiculous) different bell housing bolt patterns for all the variations of J motors that they've made. 

Probably wouldn't hurt to hit them up and ask. They're very familiar with these motors and I think they should be able to point you in the right direction. 

https://markedmotorsports.com/honda-j-series-tech-information-c-10_40.html

PHAN said:

I remember being told by Marked Motorsports that Honda has upwards of 10+ (or some number equally ridiculous) different bell housing bolt patterns for all the variations of J motors that they've made. 

Probably wouldn't hurt to hit them up and ask. They're very familiar with these motors and I think they should be able to point you in the right direction. 

https://markedmotorsports.com/honda-j-series-tech-information-c-10_40.html

Thanks for the suggestion! Just shot them an email.

Totally not just posting to bookmark this thread for later.

head design IIRC. The earlier version uses a 3-port manifold while the later uses the one large hole to the pre-cat. 

Doesn’t the A6 also have one piece cast in exhaust manifolds where the A4 does not?

penultimeta said:

Doesn’t the A6 also have one piece cast in exhaust manifolds where the A4 does not?

I think you're right, but I also think that is exactly what bobzilla said. 

Robbie said:

penultimeta said:

Doesn’t the A6 also have one piece cast in exhaust manifolds where the A4 does not?

I think you're right, but I also think that is exactly what bobzilla said. 

Can confirm. Idk about the A4 but the A6 exhaust manifolds and heads are one piece.

jeilers02 said:

Robbie said:

penultimeta said:

Doesn’t the A6 also have one piece cast in exhaust manifolds where the A4 does not?

I think you're right, but I also think that is exactly what bobzilla said. 

Can confirm. Idk about the A4 but the A6 exhaust manifolds and heads are one piece.

No, not really. It's just a different design. The manifold is one large opening now instead of 3 smaller ones. 

bobzilla said:

jeilers02 said:

Robbie said:

penultimeta said:

Doesn’t the A6 also have one piece cast in exhaust manifolds where the A4 does not?

I think you're right, but I also think that is exactly what bobzilla said. 

Can confirm. Idk about the A4 but the A6 exhaust manifolds and heads are one piece.

No, not really. It's just a different design. The manifold is one large opening now instead of 3 smaller ones. 

But as far as I can tell they're cast as a part of the head.

bobzilla said:

jeilers02 said:

Robbie said:

penultimeta said:

Doesn’t the A6 also have one piece cast in exhaust manifolds where the A4 does not?

I think you're right, but I also think that is exactly what bobzilla said. 

Can confirm. Idk about the A4 but the A6 exhaust manifolds and heads are one piece.

No, not really. It's just a different design. The manifold is one large opening now instead of 3 smaller ones. 

Well, going from the 3 cylinders to 1 output hole kind of makes it a cast-in exhaust manifold. That's what an exhaust manifold does, right?

Looks good for turbo

I imagine it impedes performance to have that "in-head manifold" design but it should make this an easier swap candidate, right?  Simply thinking about exhaust manifold and routing challenges when swapping into different chassis.

pres589 (djronnebaum) said:

I imagine it impedes performance to have that "in-head manifold" design but it should make this an easier swap candidate, right?  Simply thinking about exhaust manifold and routing challenges when swapping into different chassis.

I believe it should make it tons easier! And the hole itself shouldn't impede flow as it's actually pretty open.

It's not the size of the outlet that has me hung up.  It's the length and diameter of the primary "pipes" and the way they merge. Really good headers are quite a bit longer and come together cleaner than what this looks like to me.

Would be interesting to see what these things flow like with the older separate manifold setup vs. one of these.   

pres589 (djronnebaum) said:

It's not the size of the outlet that has me hung up.  It's the length and diameter of the primary "pipes" and the way they merge. Really good headers are quite a bit longer and come together cleaner than what this looks like to me.

Would be interesting to see what these things flow like with the older separate manifold setup vs. one of these.   

That makes more sense. Would be pretty interesting to see

pres589 (djronnebaum) said:

It's not the size of the outlet that has me hung up.  It's the length and diameter of the primary "pipes" and the way they merge. Really good headers are quite a bit longer and come together cleaner than what this looks like to me.

Would be interesting to see what these things flow like with the older separate manifold setup vs. one of these.   

The OEM trend is to tuned intakes and the exhaust doesn't matter as long as the cat lights off okay.  The power didn't drop with the engine change, did it?  Nope, integrated exhaust has 15 more horsepower and 8 more ft-lb...

Are you assuming there were no other changes to the engine other than going from bespoke exhaust manifold pipes to a merged, single outlet at the head setup?  Seems like a leap to me...  Agreed on getting the cat hot and lit off sooner as a primary goal, power second with this setup.